Faster window resize in a composite manager

[David Reveman]

On Tue, 2007-10-16 at 14:54 +0200, Dennis Kasprzyk wrote:
> Hi,
> 
> I've implemented my idea from my "Idea how to fix slow window resize in a 
> composited desktop" post. My patches add a new function 
> XCompositeSetWindowPixmapSize to Xcomposite. The compositing manager can use 
> this function to set the window pixmap to the desired size, and the xserver 
> will not change the pixmap and it's size during a resize. If 
> XCompositeSetWindowPixmapSize is called with 0/0 as size, the xserver 
> switches back to it's current pixmap handling and resizes the current pixmap 
> back to the window size.

I fail to see how this would improve performance while my suggestion of
reparenting the window we're resizing to a larger temporary top level
window doesn't. It should end up the same thing as far as the DDX care,
or am I missing something?

-David